04-BS-15 · December 2019
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams December 2019 — 04-BS-15, Engineering Graphics and Design Process (3-hour, closed-book, no calculator; 6 questions, 100 marks total; all sketches freehand, no straightedge).
Reference texts: Bertoline & Wiebe, Technical Graphics Communication (4th ed.) — orthographic/isometric/section-view theory; Giesecke et al., Technical Drawing / Engineering Graphics (15th ed.) — ASME Y14.5 dimensioning and glass-box projection theory; Ulrich & Eppinger, Product Design and Development (7th ed.); Hibbeler, Mechanics of Materials (10th ed.).
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
The question specifies “for one of the following products”: unlike the exam's other multi-part questions, this is a genuine either/or choice built into the question itself (the same convention as a per-question “sketch two of the three section types” item elsewhere in this subject), so a single, fully worked product is the complete, correct answer rather than a partial answer to all four. Product chosen: a) a hot water kettle.
A customer need is a qualitative statement, in the customer's own words, of what the product must do or how it must feel to use — it says nothing about how the design achieves it. A product design specification (PDS) restates that need as a measurable, verifiable engineering target: a specific metric, a target value or range, and a unit, so that a finished design can be objectively checked against it. Deriving specifications from needs (the core of the House-of-Quality/QFD method) is what turns a marketing wish-list into something a design team can actually engineer to and test against.
| # | Customer need (voice of the customer) | Product design specification (engineering metric) |
|---|---|---|
| 1 | “It boils water quickly.” | Time to boil 1.0 L of water from 20°C ≤ 270 s at 120 V (the heating energy is 1.0 kg × 4.186 kJ/kg·K × 80 K ≈ 335 kJ; a 1500 W element at ≈ 90% efficiency delivers it in ≈ 250 s, and 1500 W is the practical limit on a standard 15 A household circuit). |
| 2 | “It is safe to leave unattended.” | Automatic thermal cut-off shall de-energize the element within 2 s of dry-boil or over-temperature condition; complies with CSA C22.2 No. 64 (household cooking and liquid-heating appliances). |
| 3 | “The handle doesn’t get hot.” | Handle surface temperature ≤ 43°C after 10 min of continuous boil, measured per CSA touch-temperature test. |
| 4 | “It doesn’t drip when I pour.” | Spout dispenses at a pour angle of 30–60° from vertical with ≤ 2 mL residual dripback per pour, verified by repeatable bench test. |
| 5 | “It’s easy to see how much water is inside.” | Translucent/graduated water-level window, legible from a 1 m standing viewing distance, marked in 100 mL increments from 0.5–1.7 L. |
| 6 | “It fits under my kitchen cabinets.” | Overall height with lid closed on its base ≤ 250 mm. |
The correlation between the two columns is direct but not one-to-one: a single vague need (“boils quickly”) maps to one crisp, testable specification (time-to-boil under load), while a safety-flavoured need (“safe to leave unattended”) maps to a specification that references an external regulatory standard rather than an in-house test, because independently-verified compliance is itself part of what makes the customer's trust justified. Some specifications also interact or trade off against one another — a smaller overall height (need 6) constrains the element's power density needed to hit the boil-time target (need 1), and a highly insulated, cool-touch handle (need 3) adds wall thickness that competes with the compact-height target — which is exactly why the specification table, not the informal needs list, is what the design team optimizes against: it exposes those conflicts numerically (time vs. power vs. size vs. temperature) instead of leaving them as competing adjectives.
